Twins Danny and Josh are having a miserable time at camp when mad scientist Petty Potts arrives, armed with her new AMPHISWITCH formula, just in time to get another camper out of trouble.

At the zoo, twins Josh and Danny willingly try out Petty Pott's new REPTOSWITCH formula and enjoy being snakes until they are spotted by a group of girls on a field trip, including their camp friend, Charlie.

Seven-year-olds Bradley, Brian, Nate, and Lucy make observations and gather clues that convince them that their older siblings, cousin, and animals have been captured by hungry space aliens.

In the tenth book of the Calendar Mysteries, an early chapter-book mystery series featuring the younger siblings of the A to Z Mysteries detectives, there's a haunted house in Green Lawn! It's Halloween, and the Shangri-la Hotel has been transformed into a haunted house, complete with an ogre out front. Bradley, Brian, Nate, and Lucy are ready for some scary fun, but then they notice that none of the kids who have gone in the hotel have come back...

Bradley, Brian, Nate, and Lucy follow clues to find whoever left a rabbit in their first-grade classroom on Valentine's Day, because they are worried the rabbit will get sick and die of loneliness.

"Three kids must save the world from the diabolical schemes of an evil breakfast cereal company, which has been luring magical creatures to our world through a rift in the time-space continuum"--Provided by publisher.

While on vacation with their parents in Cornwall, twins Danny and Josh follow clues to another marble but find themselves trapped by the tide on a rocky island and the only way back is to use some pilfered REPTOSWITCH.

"Twelve-year-old twins Bickford and Rebecca Kidd and their two older siblings travel to Africa to track down priceless artifacts that will keep the family's treasure hunting business afloat long enough to rescue their kidnapped mother--and possibly find their missing father"--

When their two worlds collide in seventh grade, fraternal twins and opposites Owen and Russell find themselves in direct competition at school, on the court, and at home.

Twin brothers Lenny and Mel spend an uneventful summer that climaxes with a lackluster vacation.